Nuts are considered one of the healthiest foods around, full of heart-healthy monounsaturated fats, fiber and minerals like magnesium and potassium. So it may surprise you if eating nuts — whether tree nuts, like almonds and cashews, or peanuts — leads to stomach pain and discomfort.
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Why Nuts May Cause Pain
Nuts and seeds naturally contain a compound called phytic acid, says Lily Nichols, RDN, a dietitian/nutritionist and author of Real Food for Pregnancy. "They specifically have this compound in order to protect them from sprouting before they're ready to grow," she explains. "It's evolutionary — the idea is that the seeds or nuts pass through an animal's GI system intact so it can plant in the ground and survive." (You may also hear this referred to as an "anti-nutrient.")
Problem is, for some people, phytic acid irritates the digestive system. In order to break down phytic acid, you need the enzyme phytase, but your body doesn't produce that enzyme on its own, says Nichols. Adding to the complexity, there are also tannins present in walnuts and pecans that give some people tummy trouble.
"You may be more sensitive to certain compounds than others," she says. Some nuts may aggravate you while others do not, and keeping track of your symptoms in a food journal can help you pinpoint the offender.
Know that stomach pain associated with eating nuts is likely not a true food allergy, which is a process that involves your immune system and comes with the possibility of an anaphylactic (or full-body) reaction, according to the American College of Allergy, Asthma & Immunology. What you might have is a food intolerance, explains Joseph Fiorito, MD, chair of gastroenterology at Danbury Hospital, part of Nuvance Health in Danbury, Connecticut.
If you have an intolerance to nuts, you may experience symptoms one to four hours after eating them and, along with GI upset, you may also have headache and nausea, he says.
How to Get Relief
If you feel bloated or crampy after eating nuts like almonds, cashews or pistachios, as well as peanuts (actually a legume), there are a few steps you can take to make it more comfortable for yourself. Nichols recommends tricking the nut or seed to germinate prior to eating it, which can be done by soaking it in water. In general, plan for a soak time of seven hours, she says.
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Your nuts will come out of their bath soft, so you can then use them to make nut milk (like almond milk) or cream (as in cashew cream) for recipes. Otherwise, to get them crispy and crunchy again, you'll need to dehydrate the soaked nuts in an oven at a low temperature of 150 to 170 degrees Fahrenheit for about 12 hours, says Nichols.
If all that sounds like a tall order, you can speed up the process by using a dehydrator or, even quicker, by buying nuts that are already sprouted, which are available in some grocery stores. (Living Intentions is one such brand.)
Other Reasons for Discomfort
Several other factors can cause pain after eating nuts. For one, how big of a portion are you eating in one sitting? Your body may have trouble digesting a large amount of fat at once. You could also be eating too fast. "Large, undigested food particles put a strain on your digestive system," says Nichols.
Note that if you're perhaps eating a large quantity of nuts at once, it may be because there's something lacking in your diet elsewhere, and that possibility shouldn't be discounted.
"I've observed that people who are overeating nuts are often doing so because they're not eating enough at meals, especially when it comes to protein," says Nichols. Consider your overall diet and habits and be honest with yourself if you're consciously undereating.